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Cost Estimation

Infrastructure costs only (AWS). OpenAI API costs are billed separately by OpenAI.

Assumptions

  • Region: us-east-1 (N. Virginia)
  • Team size: ~20 developers
  • Average request payload: ~50 KB (request + response log)

Per-Service Breakdown

Lambda

  • Runtime: Go on provided.al2023
  • Memory: 512 MB
  • Average duration: ~20s (depends on OpenAI response time)
  • Provisioned concurrency: 2 instances
Scenario Requests/month Lambda Cost
Low 20,000 < $1
Moderate 60,000 $1-2
High 150,000 $2-4

Provisioned concurrency adds ~$5-7/month for 2 instances.

Lambda Function URL

No additional charge (included in Lambda pricing).

DynamoDB

  • Billing: Pay-per-request (on-demand)
  • Operations: 1 GetItem per proxy request
Scenario Reads/month DynamoDB Cost
Low 20,000 < $0.50
Moderate 60,000 ~$1
High 150,000 ~$2

Secrets Manager

  • 1 secret (OpenAI API key)
  • Cached in Lambda memory after first call

Cost: ~$0.50/month (fixed).

S3

  • Storage: ~50 KB per log entry
  • Lifecycle: 90-day expiration
Scenario Objects/month Storage S3 Cost
Low 20,000 ~1 GB $1-2
Moderate 60,000 ~3 GB $3-5
High 150,000 ~7.5 GB $8-12

Costs include PUT requests ($0.005 per 1,000) and storage ($0.023/GB/month).

CloudWatch Logs

Lambda execution logs only (not the proxy logs, which go to S3).

Scenario Ingestion CloudWatch Cost
Low Minimal $0
Moderate ~100 MB $0-1
High ~250 MB $1-2

Total Monthly Cost

Scenario Requests/month Total (infra)
Low ~20,000 (~1k/dev) ~$2-4
Moderate ~60,000 (~3k/dev) ~$6-10
High ~150,000 (~7.5k/dev) ~$14-22

With provisioned concurrency (recommended): add ~$5-7/month.

Notes

  • Prices based on us-east-1 as of early 2026; check AWS pricing for your region
  • Data transfer out (Lambda -> developer) is minimal and usually within free tier
  • The dominant cost for most teams will be the OpenAI API usage, not the proxy infrastructure
  • Use scripts/usage-report.py to estimate OpenAI costs per developer from the S3 logs